In Pursuit of Cairn

 is a quest in Tyranny.

Synopsis
The way to Cairn has been opened and the Scarlet Chorus can proceed to Howling Rock. There, Cairn can be destroyed and the Edict of Stone ended once and for all.

Walkthrough

 * Travel to Howling Rock in order to uncover the final resting place of Cairn's remains.
 * Cairn is currently surrounded by a guild of Earthshakers. Scout their compound to find a way inside.
 * You can't jump over the gap, so it's time for a little bit of subtlety. Head south-east to the palisade and examine it. Rolo will recall a bad story of how he got sprayed by a Beastwoman with musk (don't ask). He will also share that Basilon has a staff of pure Azurelith that can be used to access the camp.
 * Relay your findings to Octave on using a Shard of Pure Azurelith to infiltrate the Earthshaker compound.
 * Find the Earthshaker commander. If you resolved the stalemate peacefully or killed Basilon, you already have it. Use it to enter the compound.
 * The Earthshakers are performing a ritual. Stop it by breaking the staves embedded in the Azurelith lodes throughout Howling Rock. Oh, and do slaughter everyone who stands in your way, including Radix Ironcore and Caedis (if you did not kill him in Battle at Jagged Maw Shrine). Simply interact with the staves to destroy them.
 * If, during Battle at Jagged Maw Shrine, you impaled Caedis using his own sword, you can use his head to taunt Radix.
 * Approach Cairn and destroy him.
 * Talk to Octave, then harvest a piece of him (Cairn, not Octave) to empower yourself.
 * Return to Nerat.